It has changed the way we shop, the way we bank and the way we travel.

It has changed the way we get information, and the way we share it.

It has changed the way our country protects itself. And it has changed the types of attacks we must guard against.

Some of our top national security officials – including General Martin Dempsey, Chairman of the Joint Chiefs of Staff; General David Petraeus, Director of the CIA; and Leon Panetta, Secretary of Defense – have said malicious cyber attacks are among the most urgent threats to our country.

We’ve already seen cyber attacks on our nuclear infrastructure, our Defense Department’s most advanced weapons, the NASDAQ stock exchange and most major corporations.

These attacks cost our economy billions of dollars a year, and thousands of jobs. So we need to act quickly to pass legislation to make our nation safer and protect American jobs.

The Defense Department, Department of Homeland Security and experts from across the intelligence community have issued chilling warnings about the seriousness of this threat.

Only days ago, Senator McConnell and I received a letter from a remarkable, bipartisan group of former national security officials.

The group includes six former Bush and Obama Administration officials: Michael Chertoff, Paul Wolfowitz, Mike McConnell, General Michael Hayden, Retired General James Cartwright and William Lynn III.

The letter presented the danger in stark terms:

“We carry the burden of knowing that 9/11 might have been averted with the intelligence that existed at the time. We do not want to be in the same position again when ‘cyber 9/11’ hits – it is not a question of whether this will happen; it is a question of ‘when.’”

The group called the threat of a cyber attack “imminent.” And they said it “represents the most serious challenge to our national security since the onset of the nuclear age sixty years ago.”

The letter noted that the top cyber security priority is safeguarding critical infrastructure – the computer networks that control our electrical grid, water supplies and sewers, nuclear plants, energy pipelines, communications systems and financial systems.

These vital networks must be required to meet minimum cyber security standards.

The letter was clear that securing this infrastructure must be part of any cyber security legislation Congress considers.

General Keith Alexander, director of the National Security Agency, has said the same thing.

This is what he wrote to Senator McCain recently:

“Critical infrastructure protection needs to be addressed in any cyber security legislation. The risk is simply too great considering the reality of our interconnected and interdependent world.”

General Alexander is one voice among many:

The President of the United States, President Obama

The non-partisan Center for Strategic and International Studies Commission on Cyber Security

The co-chairmen of the 9-11 Commission, Governor Thomas Kean and Congressman Lee Hamilton

The Director of National Intelligence, James Clapper

The Director of the FBI, Robert Mueller

They have all echoed this call to action.

In fact, the entire national security establishment – including leading officials from the Bush and Obama Administrations, civilian and military leaders, Republicans and Democrats – agree on the urgent need to protect this vital infrastructure.

And yet some key Republicans continue to argue we should do nothing to secure critical infrastructure.

When virtually every intelligence expert says we need to secure the systems that make the lights come on, inaction is not an option.

A coalition of Democrats and Republicans – including Senators Lieberman, Collins, Rockefeller and Feinstein – has proposed one approach to address this problem.

Their bill is an excellent piece of legislation, and it’s been endorsed by many members of the national security community.

It’s a good approach, and it would make our nation safer. But there are many possible solutions to this urgent challenge.

Unfortunately, the critics of the bill have failed to offer any alternative to securing our nation’s critical infrastructure.

The longer we argue over how to tackle this problem, the longer our power plants, financial systems and water infrastructure go unprotected.

Everyone knows this Congress can’t pass laws that don’t have broad, bipartisan support. So we’ll need to work together on a bill that addresses the concerns of lawmakers on both sides of the aisle.

But for that to happen, more of my Republican colleagues need to start taking this threat seriously.

It is time for them to participate productively in the conversation, instead of just criticizing the current approach.

There is room for more good ideas on the table. And I welcome to the discussion any Republican genuinely interested in being part of the solution.

But national security experts agree: we can’t afford to waste any more time.